1. Field of the Invention
This invention relates to flood covers and more particularly to a locking system for use in conjunction therewith.
2. Description of the Prior Art
In the telecommunications industry, pedestal closures are used to provide a place where cable pairs may be interconnected to each other. Such interconnections are made at a connector block which is mounted inside the closure. The connector block includes a number of terminals and the pairs of wires in the cable are stripped of their insulation and connected to the terminals. It is quite important that moisture be prevented from reaching the exposed portions of the cable at the terminals.
In some instances it may be required to locate the pedestal closures in areas, such as the Gulf Coast of the U.S., which are subject to periodic flooding. It is, therefore, necessary to provide a cover for the pedestal closure which will prevent the flood waters from reaching the terminals of the connector block. This flood cover is a separate cover because normal conditions require internal ventilation of the pedestal. When flooding is expected the cover is placed over the regular cover of the pedestal closure. In the presence of flood waters a volume of air is trapped inside the flood cover due to the bell jar effect. This trapped air prevents the water from rising inside the flood cover. By appropriate sizing of this volume of air and by properly selecting the position of the mouth of the flood cover in relation to the connector block the flood waters may be prevented from reaching the block's terminals.
It is, however, necessary that the mouth of the flood cover be kept fixed at the selected position. Keeping the position of the mouth fixed ensures that the increased pressure on the trapped air column as flooding occurs will not try to "float" the flood cover, to relieve the increase in internal air pressure. If the mouth position were to rise, then the flood waters could rise to the level of the connector block terminals causing a service outage. Maintaining the mouth in the desired fixed position requires that the flood cover be locked to the outer surface of the pedestal cover.
Some typical techniques used to lock the flood cover to the pedestal include those which require a clamping bracket to be positioned around the pedestal column. The flood cover is then placed over the pedestal and is fastened to the clamping bracket by a bolting means or a bayonet-locking means.
Another technique involves the placing of screws at the bottom of the flood cover. The screws are then screwed radially toward the closure with opposing screws providing the locking action. This technique is not very efficient and quite often the flood cover uses a chain as an additional restraining device to prevent the cover from floating away.
A screw-clamp locking technique requires positive location of the clamping means on the pedestal. This has the potential to mar the pedestal's finish and may require additional surface preparation prior to installation, in anticipation of the use of a flood cover on that specific closure. In the presence of flood waters such marring can lead to accelerated corrosion of the pedestal. Even if the pedestal is of the non-metallic type the pressure of the fasteners, due to their geometrical shape and small contact area, can lead to indenting or fracture of the closure. Finally, if the fasteners are insufficiently tightened the position of the clamp may change, when in the presence of flood waters the flood cover tries to rise as a result of the compression of the air volume trapped inside of it.
It is therefore desirable that there be provided a flood cover which does not mar the finish of a metallic closure or indent or fracture a closure of the non-metallic type in the presence of flood waters and that it may be functionally installed on an in-place pedestal without subsequent alteration of the pedestal. It is further desirable that the flood cover be relatively easy to install and remove. It is also desirable that the cover be such that it need not be centered over the closure in order to keep the flood waters from rising to the level of the connector block.